Use generics to expand java arrays and java Arrays

Use generics to expand java arrays and java Arrays

Compile a common method. Its function is to extend the array to 10% + 10 elements (repost the source)

1 package cn. reflection; 2 3 import java. lang. reflect. array; 4 5 public class ArrayGrowTest {6 public static void main (String [] args) {7 ArrayGrowTest growTest = new ArrayGrowTest (); 8 int [] aInt = {1, 2, 3, 4}; 9 System. out. print ("original array:"); 10 growTest. printArray (aInt); 11 aInt = (int []) growTest. goodArrayGrow (aInt); 12 System. out. print ("expanded array:"); 13 growTest. printArray (aInt); 14 15 String [] aStr = {"hello", "world "," Ni "," hao "," ma "}; 16 System. out. print ("original array:"); 17 growTest. printArray (aStr); 18 aStr = (String []) growTest. goodArrayGrow (aStr); 19 System. out. print ("expanded array:"); 20 growTest. printArray (aStr); 21} 22/** 23 * array resizing method, support for different array types 24 * @ param a original array 25 * @ return newArray new array 26 */27 public Object goodArrayGrow (Object a) {28 Class cl =. getClass (); 29 if (! Cl. isArray () {30 return null; 31} 32 Class componentType = cl. getComponentType (); // use the getComponentType method of the Class to determine the type of the Array. 33 int length = Array. getLength (a); // The original length 34 int newLength = length * 11/10 + 10; // The New length 35 Object newArray = Array. newInstance (componentType, newLength); // instance the new array 36 // assign a value to the new array. a indicates the original array. The first 0 indicates the start position of the original array copy, and newArray indicates the new array, the second 0 represents the starting position of the new array value, and the length represents the length from the original array to the new array 37 System. arraycopy (a, 0, newArray, 0, length ); 38 return newArray; 39} 40/** 41 * output array content 42 * @ param a output array 43 */44 public void printArray (Object) {45 Class cl =. getClass (); 46 if (! Cl. isArray () {47 return; 48} 49 Class componentType = cl. getComponentType (); 50 int length = Array. getLength (a); 51 System. out. print (componentType. getName () + "[" + length + "] = {"); 52 for (int I = 0; I <length; I ++) {53 System. out. print (Array. get (a, I) + ""); 54} 55 System. out. println ("}"); 56} 57 58}